Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper. Spread the peach slices out in a single layer and sprinkle with the brown sugar and salt. Roast until golden and caramely, flipping once or twice during roast time, about 30 to 35 minutes.
While the peaches are roasting, stir together the graham crumbs and melted butter. Use your hands to clump together chunks of graham crumbs. Spread the mixture out on parchment so the butter can dry, even if the crumbs are still, well… crumbs.
In a bowl, whisk together the sweetened condensed milk, vanilla extract and bourbon until combined.
Place the cold cream in the bowl of an electric mixer and beat on medium high speed until stiff peaks form. Fold the whipped cream into the mixture – constantly folding over and over until everything is combined. This will take a few minutes! Fold in the sugar roasted peaches, reserving a few for the top of the ice cream. Gently stir in most of the graham chunks too. Pour the mixture into a parchment-lined loaf pan or a freezer container. Freeze for at least 6 hours (or overnight) for best results.
When serving, top with extra graham crumbs or granola if desired!